1. Field of the Invention
The present invention generally relates to the manufacturing of active and/or passive integrated circuits, and more specifically to the forming of trenches and/or of wells having different destinations in a semiconductor substrate.
In the present description, “trenches” is used to designate a cavity having, in top view, an elongated shape, for example, a strip shape that may extend in a closed contour, and “well” is used to designate a cavity having in top view a compact shape, for example, a square or a circle.
The present invention applies to the forming, in the same substrate, for example, made of silicon, of at least two elements, such as contacts towards buried layers, substrate contacts, dielectric insulation areas, tridimensional capacitances, etc.
2. Discussion of the Related Art
In prior art, when it was, for example, desired to form a well for a contact to a buried layer and a trench for a tridimensional capacitance in the same substrate, the corresponding etchings used to be separately performed, due to the incompatibility in the processings performed in the well and trench after etching.
More generally, to perform different dopings or oxidations in two groups of trenches or of wells, one should etch, dope, or oxidize, then separately fill the two formed groups of these trenches and holes.